1. Technical Field
The invention relates generally to window shades, and more particularly, to a window shade assembly having a re-channeling system for a flexible shade material with non-beaded edges, two-part side channels and a single seal strip that may include an edge of flexible wrapping material used on the side channels.
2. Background Art
One of the older forms of window shading includes a roller shade, in which a flat, rectangular piece of material (typically fabric or film) is stored in rolled form on a substantially cylindrical roller core at the top edge of a window and unrolled when desired to cover the window to block a view or modulate light. These window shades are inexpensive to manufacture and can utilize a wide range of shade materials, some of which can be decorated with images or be made environmentally responsive, e.g., with self-darkening films. Spring-loaded and ratcheted roller cores are common because they eliminate the need for any visible actuating mechanism or the safety concerns of exposed cords. Corded clutch drives are also popular.
One drawback of typical roller shades is that they do not provide any significant thermal benefit, and only partial light control. These limitations derive from two causes: the thin, single-layer nature of rollable fabrics and films, and the open gaps at the sides (and also often at the top and bottom) between the shade material and the window aperture. In order to address the thermal issue, a number of solutions have been pursued. One approach was the development of double-depth cellular window shades that provide an insulating quality to the shade material. Despite their added thermal characteristics, however, edge gaps that allow free air movement around the shading material limit the thermal and light-blocking effectiveness of these window shades.
Another approach to provide both improved thermal and light control characteristics was to add opposing C-channels that are coupled to the window frame and slidingly engage edges of the shade material. In such systems, the shade material's edge is typically beaded (increasing its thickness along the edges) and the bead is retained in a closed C-shaped channel mounted to the window frame. The beading keeps the otherwise flaccid shade material constrained to be held taut and flat between the tracks, and creates a contact seal along that junction. Unfortunately, such beading makes the shade material roll up poorly as the thick beading controls the roll-up, instead of the flat area of the main material portion (unless that main portion is similarly thickened, as for instance by quilting, to a dimension not less than the bead thickness). Consequently, the roll is much larger for the same deployed length (called the “drop”) and the beads, being narrow, tend to fall in a disorderly way when rolling, causing wrinkles and uneven deployment. A “re-railer” for guiding a beaded-edge shade back into the C-channel if it is dislodged has also been developed. However, known re-railers are bulky and do not operate without an edge bead present, to be pulled back into the channel.
Another disadvantage to known C-channel tracks is that they are visually obtrusive and present a high level of drag to deployment that makes simple gravity-driven systems unreliable. The large roll and tracks, limited fabric options (typically thick quilts, tolerant of edge beading and subsequent wrinkling) and operational limitations of such bead-and-C systems have limited their acceptance in the market to a very narrow segment that values energy savings highly over other functions or appearance.
Some C-channel systems have been applied to non-beaded shade material. In these systems, however, where the edges of the shade material dislodges from the C-channels, re-channeling is extremely difficult, so these channels are typically made with a very deep engagement to minimize the risk of dislodging. In addition, like the beaded versions, these C-channels are visually obtrusive, may occupy a large part of the window area and present a high level of drag to deployment that makes gravity-driven systems unreliable.